128 ANNALS OK SCOTTISH NATURAL HISTORY 



botanists in the issue of this most useful volume. The monograph 

 is intended to give adequate descriptions of the forms named with- 

 out such descriptions in the " London Catalogue, ed. ix., or dis- 

 covered since in Britain, thus filling gaps left by Mr. F. N. Williams 

 in his treatment of the genus, in "Prodromus Florae Britannicae." 

 Mr. Linton discusses the origin of the abundance of forms on record, 

 and states reasons for the view that few if any are due (as permanent 

 forms) to hybridity. In his garden over a hundred different forms 

 have been cultivated many years and have reproduced themselves 

 freely ; yet no hybrids have shown themselves. The true causes of 

 the numerous forms he regards as the inherent tendency to variation, 

 and climatic influences, such as altitude, soil, humidity, exposure, or 

 shade influences peculiarly active in mountain regions. Hawk- 

 weeds, he considers to be "exceedingly plastic and mobile," and 

 " highly susceptible to the influences of environment." The char- 

 acters derived from branching of inflorescences and from recepta- 

 cular alveoli are discussed. A synopsis of the genus occupies pages 

 i to 8 ; while 86 pages are assigned to descriptions of the several 

 species and varieties, with notes on features of special interest, and 

 brief indications of the distribution of each form in Britain. 



Only those that must be regarded as not owing their place in 

 Britain to man's aid are noticed, yet the number recognised as 

 species amounts to 124, and the varieties and subforms of some of 

 these are numerous. Several forms are described here for the first 

 time, some of these being named by the author, others by the Rev. 

 Augustin Ley. The monograph will be found indispensable by 

 every student of the genus Hieracium. 



